Relationship With Throttle Opening; Carburetor Setting Parts - Yamaha WR450F(W) Owner's Service Manual

SETTING

Relationship with throttle opening

The flow of the fuel through the carburetor
main system is controlled by the main jet and
then, it is further regulated by the area
between the main nozzle and the jet needle.
The fuel flow relates to the diameter of the
straight portion of the jet needle with the throt-
tle 1/8 to 1/4 open and relates to the clip posi-
tion with the throttle 1/8 to 3/4 open.
Therefore, the fuel flow is balanced at each
stage of throttle opening by the combination of
the jet needle straight portion diameter, and
clip position.

Carburetor setting parts

Part name
Main jet Rich
(STD) Lean
Pilot jet Rich
(STD) Lean
Jet needle Rich
Lean
Rich
Lean
Leak jet Rich
(STD)
Lean
7 - 7
T U N
Size Part number
#185 4MX-14943-44
#182 4MX-14943-94
#180 4MX-14943-43
#178 4MX-14943-93
#175 4MX-14943-42
#172 4MX-14943-92
#170 4MX-14943-41
#168 4MX-14943-91
#165 4MX-14943-40
#162 4MX-14943-90
#55 4MX-14948-09
#52 4MX-14948-08
#50 4MX-14948-07
#48 4MX-14948-06
#45 4MX-14948-05
GDDUM 5TJ-14916-9M
GDDUN 5TJ-14916-9N
GDDUP 5TJ-14916-9P
GDDUQ 5TJ-14916-91
GDDUR 5TJ-14916-9R
GDDUS 5TJ-14916-9S
GDDUT 5TJ-14916-9T
GDDSM 5TJ-14916-AM
GDDSN 5TJ-14916-AN
GDDSP 5TJ-14916-AP
GDDSQ 5TJ-14916-A1
GDDSR 5TJ-14916-AR
GDDSS 5TJ-14916-AS
GDDST 5TJ-14916-AT
#35 4JT-1494F-01
#40 4JT-1494F-03
#45 4JT-1494F-05
#50 4JT-1494F-07
#55 4JT-1494F-09
#60 4JT-1494F-11
#65 4JT-1494F-13